Faculty Publications

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    Analysis and Design of a High-Frequency Isolated Full-Bridge ZVT CLL Resonant DC-DC Converter
    (Institute of Electrical and Electronics Engineers Inc., 2019) Patil, U.; Nagendrappa, N.
    In this paper, a new pulsewidth modulated gating scheme and a zero-voltage transition (ZVT) auxiliary circuit is proposed for a fixed frequency full-bridge CLL dc-dc resonant converter with a capacitive output filter. An approximate complex ac circuit approach is used for the steady-state analysis of the converter. The optimum design of the converter is described with the help of design curves for a sample converter of 200-W power rating operating at a switching frequency of 100 kHz. The converter with applied gating scheme and ZVT auxiliary circuit provides zero-voltage switching to all the switches for the entire variations in loading and input voltage conditions ensuring higher conversion efficiency. PSIM simulations are carried out to verify theoretical predictions about the performance of the converter for various operating conditions. Finally, experimental results are provided to verify the feasibility of the proposed converter. The theoretical, simulation, and experimental results are given and discussed. © 1972-2012 IEEE.
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    Performance evaluation of high-frequency CLL resonant DC–DC converter operated with phase-shift and modified PWM gating scheme: Analysis, design and implementation
    (Institution of Engineering and Technology, 2020) Patil, U.; Nagendrappa, N.
    Normal phase-shift and modified pulse-width modulation gating schemes are proposed for a full bridge high-frequency capacitor–inductor–inductor (CLL) resonant DC–DC converter, and its performance is analysed in this study. Detailed modelling and the steady-state analysis of the converter are performed by using the fundamental harmonic approximation approach. Various modes of the converter operation with both the gating schemes are described and examined in detail. Zero-voltage switching of all the main switches is achieved by designing the resonant converter to operate in the above resonance mode. The optimum design of the converter is illustrated with the help of a flowchart and design curves. PSIM simulation is carried out and the experimental prototype is built to substantiate theoretical performance predictions. The simulation and experimental results are presented and compared. © The Institution of Engineering and Technology 2020
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    Design and Laboratory Validation of a Grid-Interfaced Totem-Pole PFC Converter With PR Controller and Isolated Phase Modulated Converter for Solar-Powered Next-Gen EV Charging System
    (China Power Supply Society, 2025) Kanimozhi, K.; Kesavan, P.K.; Nagendrappa, N.; Balasubramanian, B.
    This paper proposes a stationery reference frame proportional-resonant (PR) controller for current control of grid-tied converters in an EV charger application. Since it is a viable alternative to rotational reference frame PI compensators in AC applications, the PR controller has been adopted for achieving zero steady state error without using any computationally intensive reference frame transformations. In this paper, a method to design the structure of PR controller and its coefficients according to the desired transient behaviour of AC signal amplitude in PFC converter current loop has been proposed. The importance of suggested PR controller design method is that the grid current magnitude is varying constantly based on the available PV power and battery charger levels which necessitates the controller to act in desired transient behaviour. So, by this way the impact of variation in system parameters have been completely overcome by operating the converter controllers appropriately in a solar powered EV charger system. To verify the effectiveness of the proposed controller design, extensive simulations and experimental studies are performed in a 1.5 kW EV charger system under various PV irradiances and charger power levels. The experimental results obtained from the laboratory prototype confirms the simulation findings. © 2025 China Power Supply Society. All rights reserved.
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    Fixed-frequency modified gating signals controlled high-frequency isolated LCL-T DC-DC resonant power converter
    (Taylor and Francis Ltd., 2025) Reddy, V.B.; Ur Rehman, M.B.; Srinivas, B.; Nagendrappa, N.
    In this paper, a fixed-frequency modified gating signals controlled LCL-T type of resonant power converter is proposed. The converter is designed to operate in lagging power factor (pf) mode to ensure zero-voltage switching (ZVS) of the inverter switches. Steady-state analysis of the converter is carried out using the Fourier series approach by considering the effect of n-harmonics. A 300 W converter is designed, and its performance is studied using PSIM simulations. It is shown that all inverter switches turn-on with ZVS for entire loading conditions with the minimum input voltage, while only one switch loses ZVS when the input voltage is maximum. Also, a small change in pulse width is enough to regulate the output voltage for wide variations in the input voltage and the load. Power loss breakdown analysis is performed. The experimental prototype of the LCL-T resonant converter is built and tested to validate the theoretical and simulation results. The results have been compared and discussed. © 2024 Informa UK Limited, trading as Taylor & Francis Group.